1. Field of the Invention
This invention relates generally to ballistic transparencies and, in one particular embodiment, to a ballistic transparency particularly useful as a bullet proof or explosion proof vehicle transparency. This invention also relates to a method of securing a ballistic transparency to a frame.
2. Technical Considerations
Ballistic transparencies have long been used for protecting the occupants of vehicles while at the same time allowing the vehicle occupants to see out of the vehicle. Ballistic transparencies, commonly referred to as “bullet proof” or “explosion proof” windows, are widely used on military vehicles and security vehicles. Conventional ballistic transparencies typically take the form of glass and/or plastic panes bonded together to form a laminated structure.
Various methods are known for mounting a ballistic transparency to a vehicle. For example, in one known method, the ballistic transparency is placed inside a specially fabricated metal casement and the casement is attached to the vehicle. However, a problem with this method is that it is difficult and time consuming to mount the transparency in the casement. Also, it is difficult to remove or replace the transparency.
In another known method, the peripheral edge of one of the glass panes of the laminate extends beyond the other panes, thus forming a projection or “lip” which can be engaged with a conventional vehicle window frame so that no specially fabricated frames or casements are required to mount the transparency in the vehicle. While this mounting method provides advantages over the casement method, a problem with this method is that under extreme loading, such as caused by severe explosive detonations and/or high velocity projectile impacts to the transparency, the projecting lip of the transparency holding the transparency in the frame can break or crack. In a worst case scenario, this can cause the transparency to partly or completely detach from the frame, subjecting the vehicle occupants to the danger of bullets or other objects entering the vehicle through the resultant opening.
Therefore, it would be advantageous to provide a ballistic transparency and a method of mounting a ballistic transparency to a frame which eliminate or reduce at least some of the problems associated with known ballistic transparencies.